1. Field of the Invention
The present invention relates to hold-type image display apparatuses such as liquid crystal displays and organic electroluminescence displays, and particularly, to a hold-type image display apparatus capable of presenting blur-reduced motion images.
2. Description of Related Art
Image display apparatuses are classified into impulse-type display apparatuses such as those employing cathode ray tubes (CRTs) that momentarily emit strong beams to display images and hold-type display apparatuses such as active-matrix display apparatuses that employ pixels with a memory function to hold an image for every frame period. An example of the active-matrix display apparatus is a liquid crystal display (LCD) employing thin-film transistors (TFTs). The LCD has pixels each including a TFT and a capacitor to hold a written image signal for a given period.
The hold-type display apparatus has a draw back of causing a blur when displaying motion images (hereinafter referred to as the motion image blur). It has been understood that the motion image blur is caused due to a slow response speed of liquid crystal. The motion image blur, however, never solves by increasing the liquid-crystal response speed because the blur is intrinsic to the hold-type display. The blur problem and a solution for it are described in Taiichiro Kurita, “Theory of Motion Image Deterioration in LCD and Method of Solving the Same,” IEICE Technical Report, EID2000-47 (2000-09), pp. 13-18. The motion image blur occurs not only on the LCD but also on the organic electroluminescence display of active-matrix type. The method of solving the motion image blur described in the above-mentioned document shortens a hold time like the impulse-type display apparatus.
The method described in the above-mentioned document needs a device to shut a backlight in synchronization with a video signal. The technique has a drawback of spoiling a feature of the hold-type display apparatus of providing flicker-free images. The technique has another problem of decreasing the brightness of a screen because the technique shortens the emission time of each pixel.